Figure 2

Histopathology and viral expression. A, C. Histological analysis of Meckel's cartilage. B, D. Histological analysis of mandibular bone. E. β-galactosidase staining of lacZ-tagged mCMV. F. Viral IE1 protein localization. In controls (A), Meckel's cartilage (MC) is composed of aligned chondrocytes bordered by a distinct perichondrial layer (pc) and is surrounded by undifferentiated mesenchyme (m). In contrast, mCMV-infected Meckel's cartilage (C) is shorter and developmentally-delayed, with misaligned chondrocytes and a disorganized perichondrium being seen. Large basophilic, pleiomorphic mesenchymal cells, some with inclusion bodies (B insert), surround the ventral and lateral regions of Meckel's cartilage and are in the perichondrium. B, D. Mandibular bone. In controls (B), the ossifying mandibular bone is characterized by matrix-depositing osteoblasts (arrow) and acidophilic trabecular osteoid (*). mCMV-infected bone (D) is dysmorphic and less ossified, with a marked decrease in acidophilic trabecular osteoid (*). Abnormal osteoblasts, some with viral inclusion bodies (arrowhead, D insert) are seen. E-F. Viral expression. β-galactosidase staining of lacZ-tagged mCMV (E) and viral IE1 protein localization (F) indicates mCMV infection in mesenchymal and perichondrial cells. Bar, A-D: 20 μm; C, D insert: 5 μm; E: 30 μm; F: 20 μm.